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  #1  
Old 04-05-2015, 10:52 PM
Arvey Fleur's Avatar
Arvey Fleur Arvey Fleur is offline
 
Join Date: Mar 2015
Location: Sacramento, CA
Posts: 50
Default FAB Carb Heat Door mo Beefy

Howdy,

Here is my beefy Filter Air Box (FAB) rebuild. At 600 hours I had cracks in the 0.0625 alum FAB plate, the door hinge was disintegrating, the cable attach lever hole was totally moofed. I know others have had similar issues with vibration in this assembly.

I used 0.125 alum plate with a 0.125 doubler/washer plate. Note the aluminum angle spanning the entire width of the FAB plate to stiffen the whole assembly. Note also the 0.125 angle brackets for the SCAT tubing flange mount. The door hinge is now baffle material sandwiched between (2) 0.040 plates - it seals MUCH better now as indicated by improved RPM drop at run-up carb heat test. Instead of the stock cable end bug thingy, the cable is now attached with a rod end for less shaky.

Seems to be holding together well so far!

Cheers!

DanR






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Last edited by Arvey Fleur : 09-20-2019 at 09:24 PM.
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  #2  
Old 11-05-2016, 04:16 PM
stevengrasley stevengrasley is offline
 
Join Date: Oct 2011
Location: Marathon, FL
Posts: 39
Default FAB carb heat door rebuild

I rebuilt the door lever at 500 hours with an attached piece of similar material but made a better attach point. Then the hinge was completely gone on one side so I rebuilt the whole thing. Here I am at 825 hours and everything is falling apart again! I like what you did! Better seals in both directions. I like the idea of a rod end so a "real bolt" can be used in the lever arm to keep if from vibrating an egg shaped hole. Nice job. I'm going to give a similar design a shot. I'll post and let you know how it holds up.
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  #3  
Old 11-05-2016, 10:42 PM
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Arvey Fleur Arvey Fleur is offline
 
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Location: Sacramento, CA
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Default Update

1000 hours and still looks perty much like it did when I first rebuilt it at 600 hours. If I were doing it again I would clean up a few things, like metal sizes...and maybe use a wire grip PN 05-16001. The heavy 0.125 plate for the top of the FAB box is good IMO, consider how everything else on a lycosaurus is like, 1/2 thick, and then the standard FAB design has this thin 0.0625 plate!


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  #4  
Old 07-08-2017, 03:12 PM
pilotmansam pilotmansam is offline
 
Join Date: Apr 2011
Location: Newberry, SC
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I am rebuilding my FAB now. I like your design. Do you recall exactly what type of baffling material you used for the carb heat door?
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  #5  
Old 07-08-2017, 08:19 PM
jbDC9 jbDC9 is offline
 
Join Date: Jan 2005
Location: Houston, TX
Posts: 790
Default

My carb heat door and hinge was coming apart a few months ago and I luckily stumbled across this post; I shamelessly copied the hinge and door design and gotta say, it works great! The air seal is much better than the original design resulting in more effective carb heat.

The baffle material I used was the stock stuff from Vans that I had leftover from the original build, black rubber type stuff with embedded fabric.
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  #6  
Old 09-20-2019, 09:25 PM
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Arvey Fleur Arvey Fleur is offline
 
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Default Picture links fixed

Picture links fixed
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  #7  
Old 09-21-2019, 05:42 AM
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snopercod snopercod is offline
 
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Location: Asheville, NC
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This is important. I had a friend who died in his Lancair because the carb heat door broke off and lodged in the carburetor throat. The design was very similar to what I see in the photos. His death prompted me to totally re-design the airbox on my Lancair so the carb hear flapper was balanced and rocked back and forth like a teeter-totter. Ram air comes in the front and heated air comes in from the back.
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  #8  
Old 09-21-2019, 08:46 AM
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Ironflight Ironflight is offline
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Quote:
Originally Posted by snopercod View Post
This is important. I had a friend who died in his Lancair because the carb heat door broke off and lodged in the carburetor throat. The design was very similar to what I see in the photos. His death prompted me to totally re-design the airbox on my Lancair so the carb hear flapper was balanced and rocked back and forth like a teeter-totter. Ram air comes in the front and heated air comes in from the back.
Sorry about your friend, but in a standard Vanís filtered air box, the carb heat door is outside of the filter - no way it can get into the carburetor throat.
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  #9  
Old 09-21-2019, 09:12 AM
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snopercod snopercod is offline
 
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Quote:
Originally Posted by Ironflight View Post
... in a standard Vanís filtered air box, the carb heat door is outside of the filter - no way it can get into the carburetor throat.
Ah, so. That's a good design, then. In a standard Lancair, the filter is in front of the carb heat door. Not so good.
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  #10  
Old 09-23-2019, 09:54 AM
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gmcjetpilot gmcjetpilot is offline
 
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There are two kinds of stock Van's air-box owners; 1) Those who will beef-up / repair their box; and 2) those who have beefed-up / repaired their air box up.

Not sure if you are supporting airbox with struts. If not consider supporting the front end of the air-box by a strut from engine. The top plate will crack sooner or later. The box cantilevered out and under a lot of vibration. Depending on how flexible or firm the air-box to cowl seal, there is induced loads. Engine and airbox moves cowl does not.

I never had big issues with the door but used a rod end to attach the cable to the lever...
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Last edited by gmcjetpilot : 09-24-2019 at 11:54 AM.
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